You could try a Windows 7 install with Windows Update off. And make sure not to install the updates that would give you the nag warning. Risky, but worth a shot I guess.
There's also a patch to disable that nag update: https://github.com/zeffy/wufuc
From the site: "Disables the "Unsupported Hardware" message in Windows Update, and allows you to continue installing updates on Windows 7 and 8.1 systems with Intel Kaby Lake, AMD Ryzen, or other unsupported processors."
Read about it in the OC forums that I frequent: https://www.overclock.net/forum/132-windows/1690905-microsoft-blocks-win-7-8-1-updates-7th-gen-intel-amd-cpus-not-true.html